(1) Field of the Invention
This invention relates to a method of continuously processing fish on board by supplying previously processed fish flesh to a kneader and adding auxiliary ingredients during the kneading to obtain surimi which is packed and kept in the frozen storage.
(2) Prior Art
Generally, Alaska pollack or like fish caught in the north ocean or other oceans are quickly collected in a mother ship and processed into surimi therein. The surimi is packed in sacks or vessels. The packages are then frozen, to be stored in the ship, landed and supplied to the market in the frozen state. The fish collected on the mother ship is usually processed in a manner as described in "Frozen Surimi 25-th Anniversary (issued by the Japan Surimi Association, Feb. 16, 1984), p. 233.
The fish collected on the mother ship is first processed by filleting it or dressing it wherein the fish is headed and scaled using a scaler. The fish is then supplied to a flesh separator to make a separated fish flesh. The separated fish flesh is washed with water and then the skin and other undesirable matters are removed to obtain a washed fish flesh, which is then dewatered. The resulting dewatered fish flesh is supplied, in predetermined quantities, to a kneader such as a silent cutter or a mixer in which the dewatered fish flesh is kneaded for a predetermined period of time. During this time, auxiliary ingredients such as sugar are added for such purposes as preventing protein denaturation as described in the Frozen Surimi 25-Anniversary. The surimi is packed in predetermined quantities in sacks or vessels by a packer and frozen storaged. All those processes, such as filleting process, washing process, and dewatering process, are substantially constituted as a continuous process where the materials are supplied and fed continuously. Nevertheless, the process of kneading the dewatered fish flesh by the kneader and adding auxiliary ingredients is a batch process wherein a constant amount of dewatered fish flesh is kneaded for a constant period of time, so that standby times are produced every time a batch of dewatered fish flesh. Particularly, the process of packing the resultant surimi in polyethylene bags or the like has to be a batch process. Therefore, it is difficult to process fish entirely continuously, and high productivity can not be obtained.
In another aspect, auxiliary ingredients such as sugar and sorbitol are added to the dewatered fish flesh in the kneader as noted above. Among such auxiliary ingredients, only sugar can prevent enough the freeze denaturation to a certain extent. If sugar is added too much, however, it makes the meat too sweet and causes discoloring of the meat during frozen storage and heating. For this reason, sugar is partly replaced with sorbitol, that is, a mixture of sugar and sorbitol is added. Further, polyphosphate is added to further improve the water-holding capacity and to increase the effectiveness of protein denaturation.
Thus, sugar, sorbitol and polyphosphate are mixed in predetermined proportions, and this auxiliary ingredient mixture is added in predetermined quantities to the dewatered fish flesh in the kneader. However, the measuring and mixing of the auxiliary ingredients and also the measuring and supplying of the auxiliary ingredient mixture are all done manually and thus requires a great deal of labor. In addition, even if the process of kneading the dewatered fish flesh in the kneader could be made to be performed as a continuous process, the rationalization or productivity improvement of the entire process up to the production of surimi can not be expected unless the process of measuring and mixing the auxiliary ingredients and supplying the auxiliary ingredient mixture are made continuous processes. Particularly, among the auxiliary ingredients sugar and sorbitol have very high water-absorptive property. This adds to the cumbersomeness of the operation described above and also requires more labor. Further, great fluctuations of the proportions, amount, or dispersibility of the mixture are caused, making the quality of surimi instable. Further, since the operation is performed in the ship which is subject to many space limitations, the improvement of the operation of incorporating the auxiliary ingredients has been strongly desired.
In a further aspect, the dewatered fish flesh that is prepared in the mother ship in the manner as described before, is manually measured and charged in predetermined quantities into the kneader, such as a silet cutter, or a mixer. Also, the auxiliary ingredient mixture is manually transported up to the conveyor, and also the level of the auxiliary ingredient mixture to be added is determined by manually measuring the mixture. A considerable number of workers, therefore, are needed for the transportation, measuring and supplying of the auxiliary ingredient mixture, and the labor is heavy physical labor. The operations of mixing sugar, sorbitol, polyphosphate, etc. to prepare the auxiliary ingredient mixture also require very heavy physical labor. Further, if the proportions of the individual auxiliary ingredients incorporated, the dispersibility of the mixture, and the level of the auxiliary ingredient mixture added fluctuate greatly, it gives rise to problems in the stabilization of the quality of surimi and labor-saving and ultimately increases the cost of manufacture.